Projection system



April 10, 1928. 6

-- L. A. JONES ET AL PROJECTION SYSTEM Filed Augie, 1924 INVENTORS, Z0901 A JOJZQS EarZe Efi'chczrdsmu MORNE Y6.

Patented Apr. 10, 1928.

UNITED STATES PATENT OFFICE.

LOYD A. JONES AND EARLE E. RICHARDSON, OF ROCHESTER, YORK, ASSIGNOBS TO EASTMAN KODAK COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION 01' NEW YORK.

PROJECTION SYSTEM.

Application filed August 28, 1924. serial No. 734,799.

' Our invention relates to projection syspanying drawing wherein like reference tems and particularly to such systems decharacters indicate like parts throughout, signed for use with films havmg a base or F g. 1 represents diagrammatically a prosupport of cellulosic material, such as ord1- jectlon system embodying our invention;

narily used for the projectlon of motion plc- 2 represents diagrammatically a ro- 00 tures. ]ect1on system embodying a different orm Even where such films are not held staof our invention, and tionary for the projection of stills or Fig. 3.is a horizontal section of the cell titles, but are moved rapidly through the shown in Fig. 2.

projector, the heat at the gate may be such The projection system comprises a source 65 as to affect them injuriously. Numerous exof light 1, with the usual reflector 2; conperiments have been proposed to overcome denser 3, film gate 4, and objective 5. The this without unduly reducing illumination. film 6 is advanced past the film gate by any Among these may be mentioned screens 'for su1table mechanism indicated conventionreflecting heat rays, screens for absorbing all at 7. Positioned at any convenient 7 heat rays and'means for air-cooling the film polnt between the light and the film gate is gate. If screens for reflecting heat rays are a heat-absorbing screen 8. Near one edge made of sufficient density to be useful for of the screen is an outlet pipe 9 connected that purpose, their transmission of light rays with a suitable source of compressed air 20.

is so reduced that their utility for motion The pipe 9 has a vent at its end so formed 7 picture purposes is questionable. Heat aband situated as to release the air under sorbing screens have the disadvantage that pressure and direct it against the surface they heat up rapidly'and they then become of the screen that faces the light source 1,

radiators of heat. Liquid containing tanks as Indicated in dotted lines.

have the disadvantages that the convection We have found particularly advantageous 8 currents are objectionable and that such a screen comprising a glass support 10 on tanks are very undesirable in practice, par- Wh1ch is a gelatin layer 11 carrying heat ticularly for portable projectors suitable absorbing material. Such salts as copper for home use. Air directed across the sursulfate, copper chloride, copper acetate, copface of the film has a powerful cooling acper nitrate and zinc chloride have been found tion, but it tllSO'llfiS the effect of drying out satisfactory. These are soluble in water and the film with great rapidity, with the result a solution of them of any desired concentrathat the film is injured about as much as if tion is added to melted gelatin and coated in the means were not used. the usual way. No particular proportions 35 Our invention has among its objects to have been found to be critical, .but we have provide a system that will screen the film .found that, if the amount of salts present from rays that will efiect it injuriously, that weigh from two to six per cent of the weight will permit a high percentage of visible rays of the finished and dried gelatin film, satisto pass, in which the film will not be subfactory results are'obtained.

40 jected to harmful air currents and which is Instead of metallic salts, dyes known to not impractically cumbersome or complihave absorbent properties for red and infra cated. red rays-may be used. For instance, from WVe attain this and other objects by the one to three per cent of naphthalene green use of a screen that will absorb most of the in the finished gelatin layer has been found 45 heat rays and that will transmit most of the satisfactory.

light rays, and by releasing air under pres- It is to be understood, however, that all sure so that it willimpinge directly on the proportlons given are by way of example, screen but not on the film. The screen is and we do not limit ourselves to any parthus cooled by the expansion of the air as ticular formula. The screen is preferably well as by the passage of air over it, while mounted with the heat absorbing layer tothe film is not subjected to the dr 'ng efiect ward the light source.

of the 'air. The screen is thus ept from Certain sources of light, such as are lights,

becoming hot enough to radiate an injurious are particularly rich in ultra-violet rays and amount of heat wit in the projection system. as these have a tendency to accelerate the de- 65 Reference wlll now be made to the accomterioration or decomposition of certain cellulosic compositions, the support is preferably made of the known forms of glass that absorb ultra-violet light most strongly. There may, however, be incorporated in the gelatin layer a material that absorbs .ultra-violet rays, in which case ordinary glass would be used as a support. Such materials are known and among them ma be mentioned aesculin, beta-naphthol di-sul onic acid, beta-na hthol quinoline sulfonate, beta-naphthol qulnoline hydrochlorid. The first two dyes have been found satisfactory when present in proportions of about one to three percent; and the last two about two to six per cent of the dried gelatin layer.

We find most eflicient and practical the cell shown in Fig. 3 and in the stem of Fig. 2. The other elements of this system are the same as in Fig. 1, but for absorbing heat we use a cell having metal sides 13 wit grooves 16 in which fit two plates 8 in spaced position with the heat absorbing layer 11 of each facing inwardly. The cell is open at the top, and at the bottom is a pipe 9 having a head 14 with outlet vents 1'5 directing air, released from pressure, against the inner surfaces 11 of the screens. I

It is to be understood that numerous embodiments of our invention are possible, and we contemplate as within the scope of our invention all such modifications and equivalents as fall within the scope of the appended claims.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is: p

I 1. A projection system comprising a source of light, a film-positioning gate, a screen between said light and said gate and comprising a light transmitting support having upon one surface a thin layer having high absorptive properties for heat rays and low absorptive properties for visible rays, a source of air under pressure suflicient' to have a refrigerative effect when released, and means to release air under pressure and to direct such air, as it is released, into contact with the layer.

2. A projection system comprising a source of light, a film-positioning gate, a screen between said light and said gate and comprising a light transmitting support havingupon one surface of gelatine layer which is incorporated a material having high absorptive of light, a film-positioning properties for heat rays and low absorptive M and means to force air across and in contact I,

with the surface of said thin, gel'atine layer. 4. A projection system comprising a source of light, a film, positioning gate, a screen between said light and said gate and comprising a transparent support having upon one surface a thin layer having high absorptive properties for heat rays and low absorptive properties for visible rays, the screen having also high absorptive owers for ultra violet light, and means to orce air across and in contact with the surface of said thin heat absorptive layer.

5. 'A projection system comprising a source gate, a cell positioned between said light and said gate and having two spaced heat absorbing screens arranged transversely of the beam between the source of light and the gate, said screens comprising light transmitting supports having on their facing surfaces layers having high absorptive properties for heat rays and low absorptive properties for visible rays, means to admit and release air under pressure between said screens and at one edge of said cell.

6. A projection system comprising a source of light, a film-positioning gate, two spaced screens located transversely of the beam between the source of light and the gate, said screens comprising transparent supports hav ing on theirfacing surfaces gelatine layers in which is incorporated a material having high heat absorbing properties and high transmitting properties for visible rays, and means-for releasing air under pressure between said screens. 7 I

Signed at Rochester, New York this 22nd day of August, 1924.

LOYD A. JONES. EAR-LE E. RICHARDSON.

ion

CERTIFICATE OF CORRECTION. I

when No. 1,666,047. v Granted April 10,1928, to Lori) A. JONES ET AL. I

I It is hereby certified that error appears in the printed specification of the shove numbered patent requiring-correction as follows: Page 2, line 53, claim 2, for the word "of" read "a'' and after the word "layer" insert theword "in"; end that the said Letters Patent should be read with these corrections therein that the same may conform to the reeord'of the case in'the Patent Office.

Signed and sealed this 29th day of May,A. D. 1928,

M. Moore,

( Acting Commissionerof Patents. 

